New experimental device for infrared spectral directional emissivity measurements in a controlled environment

Abstract

A new experimental device for infrared spectral directional emissivity measurements in a controlled atmosphere is presented. The sample holder, which permits to measure spectral directional emissivity up to 1050K, is placed inside a stainless steel sample chamber that can be evacuated or filled with different gases. The signal detection is carried out by means of a Fourier transform infrared spectrometer. The experimental results focus on the capability of the device to perform emissivity measurements as a function of temperature, emission angle, and in situ surface state evolution. A careful study of the sample temperature homogeneity and the measurement method has been done, including the background radiation, the apparatus response function, and temperature differences between the sample and the blackbody radiator. As a consequence, a compact expression for the sample emissivity that generalizes those previously obtained for the direct radiometric measurement method is found. The error assessment shows that the main contribution to the emissivity uncertainty is related to the sample temperature. The overall uncertainty at intermediate temperature is estimated to be around 3% at short wavelengths. Emissivity measurements of Armco iron were used in order to check the accuracy of the experimental device. The experimental results show an excellent fit with direct emissivity data accessible in the literature, as well as with the theoretical emissivity obtained from the Hagen-Rubens relation.

Effect of Surface Oxidization on the Normal Spectral Emissivity of Straight Carbon Steel at 800–1100 K in Air

“…8), 10) and 11). As pointed out above, obvious oscillations of normal spectral emissivity appears only at the first several min from the heating start in this work, whereas those reported in the literature 2,[8][9][10][11]14) appeared at very different heating times, typically from several seconds to an hour in the oxidizing surroundings.…”

“…At 1.5 μm and 873 K, typically, such strong oscillation occurs at about 800-second heating time from the heating start. Campo et al 10) observed a number of weak oscillations over the wavelengths ranging from 1.28 to 25 μm at seven different heating times. Wen 11,14) observed few oscillations during the first-hour heating time.…”

“…Several groups of theoretical 9) and experimental work 7,8,[10][11][12][13][14] have sketchily studied the effect of surface oxidization on the spectral emissivity of various steels in the past fifteen years. In detail, Kobayashi et al 7) in 1999 surveyed the time variation in the spectral emissivity of cold-rolled steel surface in the oxidization processes by measuring the spectral emissivity with a sufficiently small time interval.…”

“…Iuchi 9) in 2003 described the modeling of behaviors of directional and polarized spectral emissivity of cold-rolling steels during the growth of oxidation films at 1.3, 1.5 and 3.4 μm, and studied the oscillations of spectral emissivity by simulations, which agreed well with the experimental results. Campo et al 10) in 2006 used a new experimental apparatus to measure the directional spectral emissivity of Armco iron in a controlled atmospheric surrounding, and also briefly evaluated the effect of surface oxidization on the spectral emissivity at the different heating times. Pujana et al 2) in 2007 investigated the spectral emissivity of 42CrMo4 steel over a wide wavelength range at several temperatures, and evaluated the spectral emissivity as a function of heating time.…”

Construction and Measurement of Normal Spectral Emissivity Device using Fourier Transform Infrared Spectrometer

“…또한 동일 물질이라 하더라도 표면의 산화된 정도나 거칠기에 따라 복 사율은 다르게 측정되며, [3,4] 측정에 필요한 여러 장치들에 의 한 위상차, [5,6] 검출기의 비 선형성, [7] 대기 복사의 영향, 그리 [8] 과 radiometric 방법이 있으며, radiometric 방법에는 direct 방법 [9] 과 indirect 방법 [10] 이 있다. 최근에는 분광 복사율 측정을 위하여 퓨리에 변환 적외선 분광기(FT-IR)를 이용한 direct 방법 [1][2][3][4][5][6]11] 이 주로 사용되고 있으며, 그 중 실험 장치의 교정과 대기 복사의 보정에 효과적인 two-temperature 방법 [5,6,11] 이 물질의 분광 복사율을 측정에 주로 이용되고 있다. 본 논문에서는 퓨리에 변환 적외선 분광기(FT-IR)를 이용 한 적외선 분광 복사율 측정 장치를 기술하고, 물질의 수직 분광 복사율 및 표면 상태에 따른 복사율 변화를 측정하였 다.…”